Shanghai health authorities are asking those who have been vaccinated against the H1N1 virus to donate blood so they can create a serum to treat seriously ill patients.
If all of this sounds vaguely familiar to you, it may be because we’ve discussed this process in the past. Two years ago, in fact, in a blog entitled Human Serum For Bird Flu?
Since that time, we’ve heard of several attempts in China to treat seriously ill bird flu patients with convalescent serum. While some successes have been reported, not all have had positive outcomes.
First today’s article from the Shanghai Daily, then we’ll revisit the subject.
By Cai Wenjun | 2009-12-3 |
SHANGHAI health authorities yesterday launched their latest drive in the fight against swine flu, calling on people who have been vaccinated against the virus to donate blood for emergency-treatment storage.
First in the queue will be 34 inoculated medical staff at the Shanghai Public Health Clinical Center, who are expected to donate blood today.
City blood-collection authorities said that general donations were also welcome as supplies were low, particularly of types A and O.
According to experts, a person starts to produce antibodies three weeks after catching swine flu or two weeks after vaccination.
Blood from these people can then be used to treat patients seriously affected by the H1N1 virus.
"Using serum from vaccinated staff to treat serious cases is mentioned in a treatment guide issued by the Ministry of Health," said Dr Lu Hongzhou, a member of city's expert panel on swine-flu treatment - and one of the 34 expected donors.
"The technology is safe and we have used it on our patients with good results," Lu said.
Harvesting serum antibodies from someone who has been vaccinated, or who has contracted a disease and recovered, is not a new idea. In fact the first controlled clinical trial, Fibiger’s trial of serum treatment of Diptheria, dates back to 1898.
During the great pandemic of 1918, serum treatments were tried, but the results were often disappointing.
In recent years Chinese scientists have suggested infecting horses with an attenuated (weakened) H5N1 and producing a serum.
The process is relatively simple. Once someone (or an animal) is able to produce antibodies, a quantity of blood can be removed and through a process called plasmapheresis, the blood cells are removed from the blood plasma.
This is done by passing the blood through a special filter, or by using a centrifuge. The blood plasma will contain antibodies that could then be injected into people.
A serum could, theoretically, be used as either a treatment for someone already infected, or as a prophylactic, to prevent infection.
There are problems involved, however.
It takes a large amount of blood product to produce a small amount of serum. Human donors would have to be screened for AIDS and Hepatitis, among other blood borne diseases.
Horse serum is still used today, although sparingly, because of `serum sickness’, a reaction to the serum that can be fatal.
And lastly, a serum is not a vaccine. It confers a temporary immunity, not a permanent one.
A PLoS One study from August of 2008 followed the treatment, and course of illness, of 26 Chinese H5N1 patients. Convalescent plasma – or serum – was tried with success on a couple of them.
Out of 26 patients in this study, 17 (65%) died.
While antiviral therapy was the primary treatment, Two patients also received experimental blood plasma from previously infected survivors of the H5N1 virus.
From the PLoS Study.
Two critically ill adult H5N1 cases (31-year-old male, 44-year-old female) with ARDS were treated with convalescent plasma obtained from one of two fully recovered H5N1 adult donor cases.
Plasma was obtained 129 days after illness onset from an adult female case and 81 days after illness onset from an adult male case. Both donors' convalescent plasma tested negative for hepatitis B, hepatitis C, and HIV, and were separated and heat-inactivated at 56°C for 10 h before transfusion.
The male ARDS case received three units (200 mL/unit) of transfused convalescent plasma from the female donor for 2 days, beginning on illness day 13. His H5N1 viral titre in bronchial-alveolar lavage fluid declined substantially and was undetectable for the next 3 consecutive days after receipt of the third convalescent plasma dose.
The female ARDS case, who had a history of bronchiectasis, received one unit (200 mL) of transfused convalescent plasma from the male donor once daily for 3 days, starting on illness day 13. Further virological testing has not been done for this case. Both cases also received oseltamivir (75 mg po BID) on illness days 10–14 and days 8–12, respectively.
Both cases recovered fully and were discharged home.
Fascinating stuff, and hopefully we’ll get some good data out these trials in China.